1. Field of the Invention
This invention is directed to a thermal transfer device, such as a cold plate for use in indirectly cooling objects with a cooling liquid and, more particularly, to a thermal transfer device having spiral fluid pathways for efficiently conducting a cooling fluid into indirect thermal contact with an object to be cooled.
2. Description of the Related Art
Cold plates are well-known thermal transfer devices used for cooling objects that generate excessive heat, such as, without limitation, computer chips. Cold plates are generally placed into thermal contact with the object to be cooled, and pass a cooling liquid over a surface which separates the liquid from the actual object to be cooled. In this fashion, heat may be transferred between the fluid and the object, without the fluid ever coming into direct contact with the object.
Direct contact is generally avoided, because the properties of many cooling fluids may be deleterious to the object to be cooled, or toxic to the environment, so it is preferred that the fluid be contained within a sealed environment. At the very least, it is preferred that the cooling fluid be re-circulated for efficiency and economy.
To improve the efficiency of heat transfer, it is widely known to maximize the amount of surface area of the heat transfer surfaces that comes in contact with the heat transfer fluid. There is a limit, however, as to how this has been accomplished to date. For example, it is common to form the heat transfer surface which comes into contact with the heat transfer fluid with protrusions, such as fins, to increase the amount of surface area which interfaces with the heat transfer fluid. The addition of fins, however has the unwanted effect of interfering with the flow of the thermal transfer fluid, thereby lowering the rate of thermal transfer and impairing the overall efficiency of the thermal transfer device.
Although cold plates are generally well known and widely used, there is a continuing need to make cold plates more efficient, and, therefore, more competitive, cost-effective and useful. It is especially useful to provide a single cold plate that can be used for cooling two objects at the same time, such as two computer chips operating in a computer without having to install two separate cold plates.
It will also be appreciated by one of ordinary skill in the art that a “cold plate” can be used to heat an object, if the application calls for it, so that the heat transfer fluid is at a higher temperature than the object to be warmed. For ease of reference, however, thermal transfer devices may be called herein “cold plates” even though the same structure, in a different application, may in fact be used to heat an object.